Backflow preventor with adjustable outflow direction

ABSTRACT

A backflow preventor which permits adjustment of the outflow direction is provided. A conduit provides fluid communication between the two valves of the backflow preventor. The conduit can be separated, e.g., by cutting along a groove, leaving annular flat regions. The annular flats are configured to engage with a coupler to provide leak-free connection between the separated portions of the conduit. The separated portions of the conduit can be rotated to adjust the outflow direction. Preferably, an infinite number of outflow directions are possible, all of which lie in a plane parallel to the inflow direction.

This is a continuation of application Ser. No. 09/566,771 filed May 8,2000, which is a continuation of application Ser. No. 08/970,592 filedNov. 14, 1997 (now abandoned), which is a continuation of applicationSer. No. 08/613,015 filed Mar. 8, 1996 (now abandoned), which is acontinuation of application Ser. No. 08/328,216 filed Oct. 25, 1994 (nowU.S. Pat. No. 5,503,176), which is a continuation of application Ser.No. 08/046,337 filed Apr. 12, 1993 (now U.S. Pat. No. 5,385,166), whichis a continuation of application Ser. No. 07/848,574 filed Mar. 9, 1992(now U.S. Pat. No. 5,226,441), which is a continuation-in-part ofapplication Ser. No. 07/650,799 filed Feb. 5, 1991 (now U.S. Pat. No.5,107,888), which is a continuation-in-part of application Ser. No.07/435,870 filed Nov. 13, 1989 (now U.S. Pat. No. 4,989,635), all ofwhich are incorporated herein by reference in their entireties.

The present invention relates to a backflow preventor and, inparticular, to a preventor with a provision for adjusting the outletdirection.

BACKGROUND OF THE INVENTION

Check valves are well known for use in assuring that a flow through aconduit occurs only in a predefined direction. Check valves are used,for example, in backflow prevention assemblies to prevent backflow ofone fluid body into another. Back flow prevention is often used inconnection with protecting potable water supplies from contaminantswhich could otherwise be introduced into it via back-siphonage orback-pressure. Many backflow preventors are designed to accommodatepressure commonly encountered in municipal water supplies, such as 150psi (1030 kPa) or more.

Several factors are important in designing or selecting a backflowpreventor for a particular use, including performance (e.g., minimizingpressure drop), serviceability, and ease and cost of installation.

Many backflow preventors are configured such that the direction of inletand the direction of outlet flow are predetermined. In these devices,when it is desired to provide an outlet flow direction that is different(with respect to the inlet flow direction) from the predetermineddirection, additional fittings such as elbows, U-joints, L-joints,T-joints and the like, must be connected. These additional fittings notonly add to the cost of parts, labor and design involved in installingthese devices, but also contribute to undesirable pressure loss. Theseadditional fittings further take up volume and thus are impractical inapplications having close clearances. Such pressure loss can beparticularly troublesome in applications where maintenance of pressureis important such as in fire protection systems and high rise buildings.

In previous devices, maximizing serviceability has been incompatiblewith also maximizing the performance and installation factors. Thus, inpast devices, efforts to increase the performance and ease ofinstallation has produced devices with decreased serviceability. FIG. 6depicts, schematically, a previous backflow preventor 110 whichattempted to provide ease of serviceability by including both valves in112 a, 112 b in a vertical configuration and a cover 114 which, whenremoved, permits access to the valves 112 a, 112 b (e.g., formaintenance purposes) in a vertical direction. The device shown in FIG.6, however, provides a less than optimal performance. This is at leastpartially because, owing to the orientation of the valves 112 a, 112 bwith respect to the inlet opening 116 and outlet opening 118 flowthrough the valve openings 116, 118 is forced to follow a divergent path(indicated by solid arrow streamlines 120 a, 120 b). The blocking actionof the valve disks 122 a, 122 b, causing this divergent flow 120 a, 120b, provides resistance to flow through the backflow preventor 110 andincreases the pressure drop which the backflow preventor produces.

The device depicted in FIG. 6 also has deficiencies from the point ofview of installation. In general terms, the cost of installation isleast when the backflow preventor occupies the smallest amount of space.Thus, when a backflow preventor is installed in a building, it isdesired to minimize the floor space required for installation. When thebackflow preventor is installed outside a building, the expense ofinstallation is related to the size of the enclosure required (e.g.,enclosure 132 depicted in FIG. 7). When the backflow preventor isinstalled underground, it is desirable to minimize the size of thetrench (not shown) required for underground installation.

As seen in FIG. 6, the inlet conduit and outlet conduit 124, 126 occupya horizontal distance 128 which determines the minimum amount of spacetheoretically needed for installation of a backflow preventor. The upperportion 134 of the backflow preventor 110 occupies a horizontal extent136 which is only slightly greater than theoretically minimum horizontalextent 128 required for installation. However, the lower portion 138 hasa minimum horizontal extent 142 which is substantially greater,principally because the handle portions 144 a, 144 b of the shutoffvalves extend outward from the housing 146 in a direction which isparallel to the axis of the conduits 124, 126 (i.e., parallel to a linepassing through the conduits 124, 126). Moreover, an even largerhorizontal expanse 148 is required to accommodate opening of the shutoffvalves since the handles 144 a, 144 b move in a direction parallel tothe axis of the conduits 124, 126.

FIG. 7 depicts another configuration for a backflow preventor which alsohas certain deficiencies. The axes 152 a, 152 b along which the firstand second check valves 154 a, 154 b extend (defined, for thesepurposes, as a line passing through the center of the inlet port of thevalves 154 a, 154 b and parallel to the direction of flow into thevalves) are parallel and both extend at an angle of about 45° tovertical. Access for maintenance is obtained by removing covers 156 a,156 b to provide openings. The openings lie in planes 158 a, 158 b whichare inclined to the horizontal by about 45°. Because neither of theopenings lies in a horizontal plane, the device does not provide foraccess in a vertical direction. This represents a drawback to theserviceability of the device in FIG. 7.

Installation of the device shown in FIG. 7 also has certain drawbacks.Installation requires certain additional parts such as 90° elbows 162 a,162 b to change the flow direction from the upward and downward flow ofthe inlet and outlet conduits 124, 126 to the horizontal flow directionof a backflow preventor 164. The size of the enclosure 132 required isrelatively large to accommodate the extra parts 162 a, 162 b and sincethe two shutoff valves 166 a, 166 b and check valves 154 a, 154 b aregenerally linearly arrayed. Because of the change in flow direction, theflanges 168 a, 168 b for installing the backflow preventor 164 arevertically oriented. This requires provision of supports 172 a, 172 bfor supporting and positioning the backflow preventor 164 at leastduring installation. As with the device depicted in FIG. 6, the checkvalves 154 a, 154 b of the device in FIG. 7 are of a type requiring thatthe flow through the valves be divergent 120 a, 120 b around the edgesof the valve disks.

FIG. 8 depicts another type of previously-provided backflow preventoralso having certain deficiencies.

The axes 152 c, 152 d, along which the first and second check valves 154a, 154 b extend, are perpendicular and both extend at an angle of 45° tovertical. Covers 156 c, 156 d cover access openings which lie in planes158 c, 158 d, neither of which lies in a horizontal plane. Additionalparts such as elbows 162 c, 162 d are required for installation. The twoshutoff valves 166 c, 166 d and the two check valves 154 c, 154 d aregenerally linearly arrayed. The means for connection 168 c, 168 d of theinlet and outlet of the stop valves 166 c, 166 d are verticallyoriented. The check valves 154 c, 154 d are of a type requiring that theflow through the valves be divergent 120 a, 120 b around the edges ofthe valve disks.

Typically, a check valve is designed to maintain its open configurationas long as there is flow through the valve. Once the flow stops or dropsbelow a predetermined value, the check valve closes. Typically, checkvalves are designed so that, once the valve is closed, the inletpressure must exceed a predetermined threshold before the valve willopen. Usually, a single structure, typically a spring, is used both toprovide the force to hold the valve closed (until the threshold isreached), and to provide the biasing force which moves the valve fromthe opened to the closed position. Because the biasing device providessome force tending to close the valve, even during normal flowconditions, a countervailing force must be provided to counteract theclosing force and maintain the valve open, during normal flowconditions. Typically, the countervailing force is provided by the fluidmoving through the valve. Accordingly, as the pressurized fluid movesthrough the valve, some amount of work is expended in holding the valvein the open position in opposition to the biasing force tending to closethe valve. This expenditure of work causes a pressure drop across thecheck valve, so that the check valve itself necessarily creates acertain amount of loss of the pressure head. The amount of pressureminimally required at the inlet in order to maintain the valve in theopen position is termed the “hold-open pressure.” It is desirable tominimize the pressure drop or head loss during transit through the checkvalve, and, thus, it is desirable to reduce the hold-open force.Particularly, it is desirable that the hold-open force should be lessthan that from the threshold pressure. Accordingly, a number of previouscheck valves having a biasing device have been produced, which create agreater force on the valve when it is in the closed position than whenin the open position.

Many previous designs for reduced hold-open pressure check valvesinvolve providing a linkage of one or more rigid pivoting armsconnecting the clapper to the wall or body of the valve. U.S. Pat. No.980,188, issued Jan. 3, 1911, to Blauvelt, for example, discloses a flapor swing-type valve having a clapper which can pivot toward or away froma valve seat. The clapper is pivotally connected to a rigid link or armwhich, in turn, is pivotally connected to a spring.

Other valving devices include a knuckle or toggle-type linkage havingtwo or more relatively pivoting arms or links.

SUMMARY OF THE INVENTION

The present invention includes the recognition of problems in previousdevices, including those described above. According to the presentinvention, a backflow preventor is provided which permits adjustment ofthe outflow direction with respect to the inflow direction, preferablyamong an infinite number of outlet flow directions. In one embodiment,adjustment is provided by making the portion of the housing which housesthe second backflow preventor valve movable or rotatable with respect tothe section of housing which houses the first backflow preventor valve.In one embodiment, a cylindrical region of the housing connects the twovalves and this cylindrical region can be separated to permit rotationof a portion of the cylindrical housing region with respect to the otherportion. In one embodiment, the cylindrical portion includes annularshouldered flats for accommodating a pipe coupling. In one embodiment,the housing is provided as a single casting which can be separated,between the flats, by sawing or otherwise cutting through thecylindrical portion of the housing.

It has been found that performance of backflow preventors is degradedwhen the number of changes in flow direction is increased. An increasein the number of changes in average streamline flow direction tends toincrease pressure drop and degrade performance of a backflow preventor.As used herein, average streamlines can be considered to pass throughthe center of valve inlets, pass along a direction from an upstreamvalve outlet to a downstream valve inlet and pass along the centers ofconduits elsewhere. Although the above-defined average streamline isused for purposes of explanation and analysis, it is recognized thatactual flow will typically contain some amount of turbulence.Nevertheless, for purposes of explanation of the present invention, thedefined and depicted streamlines approximate the general flow directionand are believed to approximate the actual streamlines averaged in spaceand time.

FIG. 7 depicts the average streamline 182 as dotted arrows. Tracing theflow from the upper flow in the inlet conduit 182 the downward flow inthe outlet conduit 126, there is a 90° change 184 a at the first elbowjoint 162 a, a 45° change 184 b just prior to the inlet port of thefirst valve 154 a, 90° change 184 c between the inlet and outlet of thefirst valve 154 a, a 45° change 184 d downstream of the outlet of thefirst valve 154 a, a 45° change 184 e upstream of the inlet to thesecond valve 154 b, a 90° change 184 f between the inlet and the outletof the second check valve 154 b, a 45° change 184 g downstream of theoutlet from the second check valve 154 b and a 90° change 184 h at thesecond elbow 162 b. Thus, average streamline analysis shows that thereis a total of 540° of change between the inlet conduit 124 and theoutlet conduit 126.

FIG. 8 shows the average streamline 182 for the configuration depictedtherein. There is a 90° change 186 a at the first elbow joint 162 c, a45° change 186 b prior to the inlet part of the first valve 154 c, a 90°change 186 c between the inlet and outlet of the first valve 154 c, a90° change 186 d between the inlet and outlet of the second check valve154 d, a 45° change 186 e downstream of the outlet from the second checkvalve 154 d, and a 90° change 186 f at the second elbow 162 d. Thus,average streamline analysis shows that there is a total of 450° ofchange between the inlet conduit 124 and the outlet conduit 126.

A corresponding streamline analysis of the device shown in FIG. 6indicates a total flow change of about 180°.

The present invention provides for increased performance withoutunacceptably degrading serviceability or installation factors. Thepresent invention provides for a flow through open valves withoutrequiring the flow to diverge around the edges of the valve disks. Thevalve components of the present invention, rather than inhibiting flowby requiring divergence as the flow moves through the valves, tends toenhance the desired flow by directing flow along the desired path. Thepresent invention has an average streamline flow change of directiontotalling about 180°. According to an embodiment of the presentinvention access to one of the check valves is in a vertical directionwhile access to the other is in a horizontal direction. The valvespreferably extend along axes which are oriented at 90° to one another.

Valves containing a relatively large number of moving parts, such aspivoting rigid arms, are typically susceptible to wear or deterioration,particularly in corrosive, contaminated, or depositional environments,such as in hard water. Furthermore, rigid linkage systems are relativelyexpensive to design, produce, install, and maintain. Installation andmaintenance often require use of special tools.

The present invention includes a spring which connects the valve clapperto the valve body. Preferably the spring connects the clapper to aremovable cover portion of the valve body. The spring can be viewed astaking the place of one or more of the rigid links of previous devices.Preferably, the spring is directly connected to the clapper device,i.e., without an intervening linkage, and forms the sole connectionbetween the clapper device and the valve wall (preferably the coverportion of the valve wall). The spring pivots with respect to theclapper about a pivot point, with the pivot point remaining in a fixedposition with respect to both the end of the spring and the clapperdevice during opening and closing of the valve. The spring provides aforce along its longitudinal axis without a lateral component.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view through a check valving device showinga closed check valve and an opened check valve;

FIG. 1A is a partial cross-sectional view corresponding to FIG. 1, butshowing another embodiment;

FIG. 2 is a cross-sectional view taken along line 2—2 of FIG. 1; and

FIGS. 3A and 3B depict, schematically, the triangles formed by thepivoting or attachment axes or points in the closed and openedconfigurations, respectively;

FIGS. 4A and 4B depict, schematically, an unstressed helical spring anda compressed and bowed helical spring;

FIGS. 5A and 5B depict, schematically, two end-joined helical springs,in unstressed and stressed configurations, respectively;

FIG. 6 is a schematic cross-sectional view of a backflow preventoraccording to a previous device;

FIG. 7 is a schematic cross-sectional view of an enclosed backflowpreventor according to a previous device;

FIG. 8 is a schematic cross-sectional view of a backflow preventoraccording to a previous device;

FIG. 9 is a side elevational view, partly in cross-section, of abackflow preventor;

FIG. 10 is a side-elevational view of a backflow preventor; and

FIG. 11 is a side-elevational view of a backflow preventor;

FIG. 12 is a side-elevational view, partly in cross-section, of abackflow preventor, according to one embodiment of the presentinvention;

FIG. 13 is a side-elevational view of a backflow preventor, according toone embodiment of the present invention;

FIG. 14 is a cross-sectional view of portions of a backflow preventorhousing coupled by a coupler according to one-embodiment of the presentinvention;

FIG. 15 is a cross-sectional view taken along line 15—15 of FIG. 14;

FIG. 16A is a schematic simplified view of the apparatus depicted inFIG. 13;

FIG. 16B is an end view of the apparatus of FIG. 16A;

FIG. 17A is a side-elevational view of the apparatus of FIG. 16A, butwith the outlet flow direction changed by 90°;

FIG. 17B is an end view of the apparatus of FIG. 17A;

FIG. 18A is a side-elevational view of the apparatus of FIG. 16A, butwith the outlet flow direction rotated by 180°; and

FIG. 18B is an end view of the apparatus of FIG. 18A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A backflow preventor 212, according to one embodiment of the presentinvention, is depicted in FIG. 12. The backflow preventor 212 includesfirst and second shutoff valves 214 a, 214 b and first and second checkvalves 12, 14. Valves 214 a, 214, 12, 14 are encased in a housing 216. Aconduit 228 provides fluid communication between the first check valve12 and the second check valve 14. The first and second check valves 12,14 are positioned generally vertically above the inlet and outlet stopvalves 218, 220 and the second check valve and shutoff valve 14, 214 bare substantially level, but horizontally displaced from the first checkvalve and shutoff valve 12, 214 a. Thus, the flow from the first shutoffvalve 214 a to the first check valve 12 and the second check valve 14and the second shutoff valve 214 b is in a generally inverted U-shape,as opposed to a linear shape.

During the operation, fluid enters the first shutoff valve 14 a from theinlet conduit 124 in a first flow direction 268. When the flow reachesthe first check valve 12 there is a 90° change of direction 274. Theflow 272 b flows through the conduit 228 towards the second check valve14. When the flow 272 b reaches the second check valve 14, there is asecond 90° change in flow direction 282 of the average streamline 272.As can be seen from FIG. 12, the total change in direction of theaverage streamline 272 is the sum of the two changes of direction 274,282, both of which are approximately 90°, providing a total of about180° of change in direction. In the configuration depicted in FIG. 12,the direction of outflow 272 c is substantially parallel to, spacedfrom, and opposite in direction from the direction of inflow 272 a.

As depicted in FIG. 12, conduit 228 is provided with a device forpermitting adjustment of the outflow direction. In the embodiment ofFIG. 12, this device includes first and second spaced-apart annularflats 312, 314. In external, as shown in FIG. 13, the annular flats 312,314 appear as ribs or ridges spaced apart by a groove 316. The outerfaces 318, 320 of the flats 312, 314 are substantially cylindrical. Theshoulders 322, 324 connecting the flats 312, 314 to the main portion ofthe conduit 228 are preferably slightly curved. In the embodiment ofFIGS. 12 and 13 the conduit 228 and both flats 312 and 314 areintegrally formed such as from a single casting. In this way, thebackflow preventor of the present invention can be used in a firstconfiguration with the inflow direction 272 a and outflow direction 272c parallel and opposite, as shown in FIG. 12, or can be reconfigured toprovide a different outflow direction. In order to provide suchdifferent outflow direction, the conduit 228 is cut such as by sawingalong the groove 316. Preferably, the kerf created by the cut will leavesubstantially flat faces. Such cutting divides the conduit 228 into afirst portion 326 and a second portion 328. After cutting, the first andsecond portions 326, 328 are separated. The second portion 328 can nowbe moved, such as by being rotated, with respect to the first portion326, as described more fully below. After rotating, the first portionand second portion 326, 328 are connected, such as by using a couplingdevice 330 such as that depicted in FIGS. 14 and 15. The coupling 330depicted in FIGS. 14 and 15 includes a gasket, such as a rubber gasket332, a key 334 and a housing 336. The gasket 332 may be substantiallyannular in shape. Preferably, the key 334 and housing 336 are of asplit-ring type which can be drawn and held together by a connector suchas bolts 338 and nuts 340. The key 334 includes ledges 342, 344 whichengage the shoulders 322, 324 of the flats 312, 314. The coupler 330 isconfigured to provide a leak-free connection between the first andsecond portions 326, 328 of the conduit 228.

As depicted in FIG. 16A, when the conduit 228 is uncut, the inlet flowdirection 272 a and outlet flow direction 272 c, respectively defined bythe valve inlet opening 350 and outlet opening 352 are substantiallyparallel and opposite. After the conduit 228 is cut, as described above,the valve can be reconfigured to provide a different outflow direction.For example, as depicted in FIG. 17A, the right hand portion of theconduit 228 can be rotated to an angle 354 of about 90° to provide anoutlet opening 352 defining an outflow direction 272 d which isdifferent from the first outflow direction 272 c. In the configurationdepicted in FIGS. 17A and 17B, the outflow direction 272 d issubstantially at right angles to the inflow direction 272 a. Because theoutlet opening 352 can be placed in a plurality of different positions,by rotating different angles, a plurality of outflow directions,preferably an infinite number of outflow directions, can be provided. Inthe depicted embodiment, all of the outflow directions lie in a planeparallel to the inflow direction 272 a. In the configuration depicted inFIGS. 18A and 18B, the outflow opening 352 has been rotated through anangle 356 of about 180° to provide an outflow direction 272 e which isparallel to and in the same direction as the inflow direction 272 a.

A backflow preventor 212 is depicted in FIG. 9. The backflow preventor212 includes first and second shutoff valves 214 a, 214 b and first andsecond check valves 12, 14. The shutoff valves can be any of a number ofwell-known valve designs, including a ball valve, a gate valve, or,preferably, a globe valve. Preferably, the shutoff valves can bemanually opened or closed by moving external handles 269 a, 296 b. Thevalves 214 a, 214 b, 12, 14 are encased in a housing 216 which includesan inlet lower portion 218, a valve body 16, and an outlet lower portion220. A conduit 222 leads from the first shutoff valve 214 a to the inletport 224 of the first check valve 12. The inlet port 224 is preferablycircular in shape and surrounded by a valve seat 28. The inlet port 224can be closed by the clapper or valve disk 32. The valve disk 32 ismovable between a closed configuration or position (FIG. 1) and an openconfiguration as depicted in FIG. 9. The flow exits the first valveregion 12 through an outlet port 226 and enters a conduit 228 whichprovides fluid communication between the first check valve 12 and thesecond check valve 14. In the embodiment depicted in FIG. 9, the conduit228 contains a first downward sloping portion 232 imparting a shape tothe apparatus similar to the letter “N”. At the downstream end of theconduit 228 is an inlet port 234 of the second check valve 14.Surrounding the inlet port 234 is a valve seat 76. The second checkvalve 14 operates in a manner substantially similar to that of the firstcheck valve 12 as described more fully below. Flow leaves the secondcheck valve 14 to an outlet port 236 and is conveyed by a conduit 238 toa second shutoff valve 214 b.

As seen in FIG. 9, the first and second check valves 12, 14 arepositioned generally vertically above the inlet and outlet stop valves218, 220 and the second check valve and shutoff valve 14, 214 b aresubstantially level, but horizontally displaced from the first checkvalve and shutoff valve 12, 214 a. Thus, the flow from the first shutoffvalve 214 a to the first check valve 12, the second check valve 12 andthe second shutoff valve 214 b is in a generally inverted-U shaped, asopposed to a linear shape such as that depicted in FIGS. 7 and 8. Inthis way, the horizontal extent 262 of the backflow preventor 212 isreduced, compared to linear configurations such as those in FIGS. 7 and8. As can be seen from FIG. 9, the horizontal extent 262 of the backflowpreventor 212 is also reduced, compared to a configuration such as thatdepicted in FIG. 6, since the handles 264 a, 264 b by which the shutoffvalves 214 a, 214 b are operated, extend in a direction perpendicular toa line connecting the inlet and outlet conduits 124, 126. The directionin which the handles 264 a, 264 b move as the shutoff valves 214 a, 214b are opened and closed, is a direction perpendicular to a lineconnecting the conduits 124, 126. By providing shutoff valve handles 264a, 264 b which extend and move in a direction perpendicular to the lineconnecting the conduits 124, 126, the horizontal extent of the backflowpreventor 212, in a direction along the line connecting the conduits124, 126 is reduced, compared to devices such as that depicted in FIG.6.

The first check valve 12 extends generally along an axis 242. The secondcheck valve 14 extends along an axis 244. In the embodiment depicted inFIG. 9, the second check valve extends along an axis 244 which is atapproximately 90° to the axis 242 of the first check valve 12.

An opening 246 is provided in the housing 216 in the region of the firstcheck valve 12, covered by a covering 248. The covering 248 (FIG. 10) isremovably held in place by bolts 252 a, 252 b. When access to the firstcheck valve 12 is desired, such as for maintenance or installation, thebolts 258 a, 258 b are removed and the covering 248 is removed to exposethe first check valve 12 through the opening 246. As can be seen fromFIG. 9, access to the first check valve 12 is along a verticaldirection.

A second opening 254 is provided in the housing 216 in the region of thesecond check valve 14. The opening 254 is covered by a covering 256removably held in place by bolts 258 a, 258 b. When access to the secondcheck valve 14 is desired, the covering 256 is removed. As can be seenfrom FIG. 9, access to the second check valve 214 is in a horizontaldirection.

The lower portion of the backflow preventor 212 includes flanges 266 a,266 b for connection to the inlet and outlet conduits 124, 126. Becausethe flanges 266 a, 266 b are horizontally oriented, the backflowpreventor 212 can be positioned to rest on the inlet and outlet conduits124, 126 during installation, thus avoiding the need for supports suchas those 172 a, 172 b depicted in FIG. 7.

During operation, fluid enters the first shutoff valve 214 a from theinlet conduit 124 in a first flow direction 268. The average streamlineflow 272 a continues through the conduit 222 and through the inlet port224 without substantial change in direction until it reaches the valvedisk or clapper 32. As shown in FIG. 9, because of the configuration ofthe valve disk 32 flows through the inlet port 224 is substantiallystraight 276 and non-divergent. When the flow reaches the clapper 32(i.e., when any fluid “parcel” component of the flow reaches the clapper32) there is a 90° change of direction 274. When the clapper 32 is inthe open configuration, as depicted in FIG. 9, it is positioned so as todirect the flow (as analyzed by the position of the average streamline)from the first direction 272 a (i.e., substantially vertically upward)to a second direction, 272 b (i.e., substantially horizontally towardthe second check valve 13). In the embodiment depicted in FIG. 9, theclapper 32 acts as a flow director because it forms a surface positionedsubstantially at an angle with respect to the upward flow 272 a.

The flow 272 b which has been redirected by the clapper 32 exits theoutlet port 226 and flows through the conduit 228 towards the secondcheck valve 14. The flow 272 b passes through the inlet port 234 of thesecond check valve 14. During such passage, the flow is substantiallystraight and non-divergent 278. The flow 272 b proceeds from the firstcheck valve 12 to the second check valve 14 substantially without changeof direction until it reaches the clapper 72 of the second check valve14. The clapper 72 acts as a flow director, in a manner similar to thatof the first clapper 32, redirecting the flow 272 b to a verticallydownward direction to 272 c. Thus, there is a second 90° change in flowdirection 282 of the average streamline 272. As can be seen from FIG. 9,the total change in direction of the average streamline 272 is the sumof the two changes of direction 274, 282, both of which areapproximately 90°, providing a total of about 180° of change indirection.

FIG. 11 depicts a backflow preventor 286. The backflow preventor 286depicted in FIG. 11 is substantially similar to the backflow preventordepicted in FIG. 10 except for the addition of a relief valve 288 and aconduit 292. The relief valve 288 is provided in order to dischargepossibly contaminated water into the atmosphere to prevent its enteringthe water source. A number of relief valves of types well-known in theart can be used. The relief valve 288 and conduit 292 are connected tothe housing 216 in two places. The conduit 292 connects the relief valve288 to a portion of the housing 293 which is upstream of the first checkvalve 12. The relief valve 288 is also connected to a region 296 (FIG.9) which is downstream of the first check valve 12. For properoperation, the region 296 should be a distance 298 below the level 299of the inlet port 224 for the first check valve 12. This change in level298 is provided by the downward sloping portion 232. In operation, whenpressure at the upstream location 293 falls below a predetermined levelwith respect to pressure in the valve interior, the valve 288 opens topermit discharge of water.

Test cocks 297 a, 297 b, 297 c are connected to the housing 216 in orderto provide a position for pressure testing, e.g., by connecting adifferential pressure gauge.

As depicted in FIG. 1, a check valving device 10 is provided having afirst check valve 12 and a second check valve 14. A number of valves canbe used for the check valves, including those depicted in FIGS. 1 and 2.When pivoting valves are used, such as the valves depicted in FIGS. 1and 2, it is anticipated such valve with experience least wear whenconfigured in the vertical up or vertical down positions (withhorizontal pivot axes). Thus, when it is desired to avoid wear, thepreferred configurations for the adjustable outlet, using such valves,will be those depicted in FIGS. 16A and 18A. If other orientations aredesired, and wear is to be avoided, it would be preferable to mount thevalves within the housing in a position such that, after adjustingoutlet direction, the valve orientation will be vertically upward ordownward. Alternatively, it may be possible to use another type of valvewhich is less susceptible to wear in other positions. Although FIG. 1depicts the first check valve 12 in a closed position, and the secondcheck valve 14 in an open position, in actual operation, as describedmore fully below, the first and second valves 12, 14 will open and closesubstantially simultaneously or within a short time interval of oneanother. The valving device includes a valve body 16 made up of a wall18. The valve body 16 can be formed of a number of materials, includingductile iron, brass, stainless, steel, or other metals, plastic, resin,glass, and/or ceramic and the like. The valve body 16 defines an inletport 22 and an outlet port 24, preferably having a substantiallycircular cross-section. Preferably, the inlet port and outlet portinclude devices, such as flanges 26, for connecting the valving device10 to fluid conduits. Adjacent to the inlet port 22 is a valve seat 28,such as an annular seat formed, for example, of iron.

A disk-shaped clapper 32 is rigidly connected, such as by using a bolt34 and nut 36, to a clapper arm 38. A first end 39 of the arm 38 ispivotally mounted adjacent the valve seat 28 by connection to a portionof the valve body 16 by a pivot joint 42 a, 42 b to permit pivoting ofthe arm 38, and rigidly attached to disk 32 about a first axis 43.

The lower surface of the clapper 32 includes a seat disk 44 configuredto sealingly mate with the valve seat 28 when the clapper 32 is pivotedto its closed position, as depicted in the left portion of FIG. 1. Thedisk 44 can be made of a number of materials, including plastic, rubber,resin, and the like, and is preferably a soft (such as about 40durometer) elastomer material, such as a synthetic rubber e.g., EPDM(ethylene-propylene terpolymer). The disk 44 is reversible so that afterit experiences wear, it can be removed, rotated 180° about a horizontalplane, and reinstalled.

The second end 48 of the clapper arm 38 is pivotally connected to aspring 52. The spring 52 is contained between first and second springseats 54, 56. The spring 52 is preferably a helical spring which iscompressional, i.e., is reduced in length as the valve 12 opens. Thespring 52 can be formed of a number of materials, such as spring steel,plastic, or rubber. A single helical spring 52′, such as that depictedin FIG. 4A, is commonly subject to deformation when compressed. As shownin FIG. 4B, a compressed helical spring commonly assumes a bowed orarcuate configuration. Although such a spring can be used in accordancewith the present invention, according to the preferred embodiment, twosprings 52A, 52B are joined end-to-end by connection to a plate-like orannular device, such as a washer 53, as depicted in FIG. 5A. Uponcompression, as depicted in FIG. 5B, such a spring 52 tends to maintainits linear configuration and is not subject to bowing or distortion tothe degree an ordinary helical spring 52B is.

The first spring seat 54 is pivotally attached to the second end 48 ofthe clapper arm 38 to permit pivoting of the spring 52 about a secondaxis 64.

The second spring seat 56 is pivotally connected to the valve body wall18. In the preferred embodiment, the portion of the valve wall which thesecond spring seat 56 connects to is a removable cover 65 which can beattached to the remainder of the valve body wall 18, by e.g., bolts,screws, clamps, or the like (not shown). As shown in FIG. 1, the secondspring seat 56 can be connected within a pocket 58 at an attachmentpoint 62, to permit pivotal movement of the spring 52 about a third axis66.

In the embodiment depicted in FIG. 1, the second valve 14 is positioneddownstream from the first valve 12. Preferably, the second valve 14 isidentical in construction to the first valve 12, and includes a clapper72, a biasing device, such as a spring 74, and a valve seat 76. It willbe understood, however, that the present invention can be used in singlecheck valve configurations or other types of valve configurations.

Viewed in cross-section, each of the two valves 12, 14 define a trianglehaving vertices at the first axis 43, 43′, second axis 64, 64′, andthird axis 66, 66′, respectfully. When the valve 12 is closed, thespring biasing device 52 provides a force to the clapper 32, tending tohold the clapper 32 in the closed position. The amount of force isdependent upon two factors: (1) the magnitude of the longitudinal forceprovided by the spring 52; and (2) the component of that force whichacts in a direction tending to close the clapper 32. As depicted inFIGS. 3A and 3B, the spring closing force can be described as

Sin(180°−α).{overscore (F)}  (1)

where α 77, 77 ′ is the angle formed between the lines containing thefirst and second axes 43, 64, and the line containing the second andthird axes 64, 66, and {overscore (F)} 79, 79′ is the vector forceprovided by the spring along the longitudinal spring axis whichintersects the second axis 64 and third axis 66.

When the inlet pressure exceeds the outlet pressure, an opening force iscreated. When the opening force on the clapper 32 exceeds the springclosing force (shown in equation (1)) plus any closing forces providedby other sources, such as fluid pressure the clapper 32 moves away fromthe valve seat 28, opening the valve 12 to provide fluid communicationbetween the inlet port and the outlet port 24. During the openingmovement of the valve 12, the position of the second axis 64 changeswith respect to the valve body 10, but does not change with respect tothe clapper 32 or with respect to the adjacent end of the spring 52.

As the clapper 32 pivots about the first axis 43, the angle α increasesfrom a value of about 118° 77 in the configuration shown on theleft-hand portion of FIG. 1 (depicted schematically in FIG. 3A) to avalue of about 164° 77′ when in the fully opened configuration of thevalve 14, shown on the right-hand portion of FIG. 1 (depictedschematically in FIG. 3B). The magnitude of the closing force providedto the clapper 32 thus changes from about 87% of that of the springforce {overscore (F)} 79 to about 27% of that of the spring force{overscore (F)} 79′. However, during this time, the magnitude of springforce {overscore (F)} also changes, since it is proportional to thelength of the spring 52, becoming larger as the valve 12 opens. In orderto produce a valve 12 having a reduced hold-open force, the extremevalues of the angle α 77, 77′, the distance between the first and thirdaxes 43, 66, and first and second axes 43, 64 are selected so thatequation (1) yields a smaller closing force in the opened position ofthe valve (FIG. 3B) than in the closed position of the valve (FIG. 3A).

The particular values for the hold-open force, maximum tolerable headloss, and the threshold opening pressure will depend upon the particularuse or application of the valving device 10. In one embodiment of thepresent invention, valving device 10 opens when the inlet pressureexceeds the outlet pressure by about 2-5 psi (about 14-35 kPa), andcloses when the outlet pressure equals or exceeds the inlet pressure.Preferably, this embodiment has a head loss of less than 2 psi in astatic or no-flow (limiting) condition, and there is little increase inhead loss as the flow increases, such as a head loss of about 3 psi(about 20 kPa), with an operational flow velocity of about 7.5 ft./sec.(about 2.3 meters/sec.), or a rated flow velocity, e.g., 18 ft./sec.(about 5.5 meters/sec.) In another embodiment, the static condition headloss is about 8 psi (about 56 kPa), and the head loss during flowconditions remains below about 10 psi (about 70 kPa).

Based on the above description, a number of advantages of the presentinvention are apparent. The backflow preventer in the present inventionhas enhanced performance, such as lower pressure drop, and has adecreased number of changes of flow direction. By providing a device inwhich the valves are aligned 90° to each other and in which the totalchange of direction is about 180° , a backflow preventer is providedwhich has enhanced performance without substantial degradation ofserviceability.

By using the apparatus of the present invention, a backflow preventorcan be provided which provides outflow in any of a plurality ofdirections without the pressure loss and expense of providing additionalfittings. For example, it is possible to provide inflow and outflowwhich are both directed vertically upward while reducing pressure lossin pressure-sensitive applications such as fire protection and high risebuildings. By providing a housing which can be cast as a unitary pieceand, if desired, cut, the same body casting can be used, uncut in astandard device, as is used in the adjustable outlet when cut.

A number of modifications and variations of the invention can be used.The backflow preventor described above, in particular the housing andflow configuration, can be used in conjunction with check valves otherthan the check valves described, such as flapper valves with other typesof biasing mechanisms. The check valve of the present invention can beused in combination with other valves or fluid-control devices. Thevalve can be used with fluids other than liquids. The valve can beconfigured without using a clapper arm, such as by directly pivoting thespring to the clapper and/or directly pivoting the clapper adjacent thevalve seat. Other shapes and geometries of the clapper, ports, valveseats, and other components can be used. Other types of biasing devicescan be used, including springs other than helical springs, hydraulicbiasing devices, and the like. The present invention can be usedemploying other types of couplers for joining the separated portions ofthe conduit than those described and can be constructed of a variety ofmaterials. The present invention can provide for movement of the outletopening using devices other than the annular flats, such as by using arotatable sealed joint. Although in one embodiment the housing isprovided as a unitary piece which can be cut to achieve a rotation, thehousing can also be provided in two or more separate pieces, e.g.,joined by a coupling, so that it is not necessary to cut the housing inorder to perform rotation.

Although the description of the invention has included a description ofa preferred embodiment and certain modifications and variations, othermodifications and variations can also be used, within the scope of theinvention, which are described by the following claims.

What is claimed is:
 1. A backflow preventor assembly comprising: firstand second backflow preventor valves; a housing encompassing said firstand second backflow preventor valves, such that both of said valvesautomatically close if flow though said backflow preventor assemblydrops below a predetermined value, said housing including an inletopening defining an inlet flow direction, an outlet defining an outletflow direction and a conduit providing fluid communication between saidfirst and second backflow preventor valves wherein at least a firstportion of said conduit is movable with respect to a second portion ofsaid conduit to permit a change in said outlet flow direction withrespect to said inlet flow direction and said conduit includes first andsecond spaced-apart annular flats configured to accommodate a pipecoupling apparatus after being separated by cutting.
 2. A backflowpreventor assembly, as claimed in claim 1, wherein said outlet flowdirection can be changed to any of a plurality of directions.
 3. Abackflow preventor assembly, as claimed in claim 2, wherein saidplurality of flow directions lie substantially in a plane substantiallyparallel to said inlet flow direction.
 4. A backflow preventor assemblycomprising: first and second backflow preventor valves; a housingencompassing said first and second backflow preventor valves, such thatboth of said valves automatically close if flow through said backflowpreventor assembly drops below a predetermined value, said housingincluding an inlet opening defining an inlet flow direction, an outletdefining an outlet flow direction and a conduit providing fluidcommunication between said first and second backflow preventor valvesmeans for permitting movement of said outlet opening with respect tosaid inlet opening to permit a change in said outlet flow direction withrespect to said inlet flow direction, wherein said means for permittingmovement includes first and second spaced-apart annular flats on saidconduit configured to accommodate a pipe coupling apparatus after saidconduit is separated by cutting.
 5. A method for adjusting outflowdirection in a backflow preventor assembly comprising: providing firstand second backflow preventor valves; encompassing said first and secondbackflow preventor valves in a housing, such that both of said valvesautomatically close if flow through said backflow preventor assemblydrops below a predetermined value, said housing including an inletopening defining an inlet flow direction, an outlet defining an outflowdirection and a conduit providing fluid communication between said firstand second backflow preventor valves, wherein said conduit includesfirst and second spaced-apart annular flats; moving at least a firstportion of said conduit with respect to a second portion of said conduitto change said outflow direction with respect to said inlet flowdirection, cutting said housing between said first and second flats toseparate said conduit into first and second portions; rotating saidfirst portion with respect to said second portion; and connecting saidfirst and second portions with a connector.
 6. A backflow preventorapparatus for connection to parallel, oppositely-flowing inlet andoutlet conduits, comprising: a housing configured to accommodate firstand second valves, and to receive fluid flow from said inlet conduit; afirst valve mounted in said housing having a seatable valve disc havingan edge, moveable between a closed configuration preventing flow and anopen configuration permitting flow through a first inlet port in a firstdirection, said first valve mounted to extend along an axis defined bysaid first direction; and a second valve mounted in said housing havinga seatable valve disc having an edge, movable between a closedconfiguration preventing flow and an open configuration permitting flowthrough a second inlet port in a second direction, said second valvemounted to extend along an axis defined by said second direction, saidaxis of mounting of said second valve being substantially perpendicularto said axis of mounting of said first valve; said fluid flow having anaverage streamline path between said inlet and said outlet conduit,wherein the sum of changes in flow direction of said average streamlinepath is not substantially greater than about 180 degrees, furthercomprising a first flange for coupling to said inlet conduit and asecond flange for coupling to said outlet conduit.
 7. A backflowpreventor apparatus for connection to parallel, oppositely-flowing inletand outlet conduits, comprising: a housing configured to accommodatefirst and second valves, and to receive fluid flow from said inletconduit; a first valve mounted in said housing having a seatable valvedisc having an edge, moveable between a closed configuration preventingflow and an open configuration permitting flow through a first inletport in a first direction, said first valve mounted to extend along anaxis defined by said first direction; and a second valve mounted in saidhousing having a seatable valve disc having an edge, movable between aclosed configuration preventing flow and an open configurationpermitting flow through a second inlet port in a second direction, saidsecond valve mounted to extend along an axis defined by said seconddirection, said axis of mounting of said second valve beingsubstantially perpendicular to said axis of mounting of said firstvalve; said fluid flow having an average streamline path between saidinlet and said outlet conduit, wherein the sum of changes in flowdirection of said average streamline path is not substantially greaterthan about 180 degrees, further comprising at least a first shut-offvalve for shutting off flow into said first valve, wherein said firstvalve is positioned at a higher elevation than said first shut-offvalve.